OPEC members appear to be complying with agreed production cuts, but Saudi Arabia is overcompensating for some of its fellow oil producers.
The OPEC deal, agreed late last year, requires 10 member states to reduce their collective output by 1.2 million barrels per day (bpd) starting from January 1.
S&P Global Platts, which monitors monthly OPEC production, released its latest survey earlier this week and found members achieved 91 percent of their required cuts for the month of January, or 1.14 million bpd.
"OPEC spent much of the last half of last year talking up this deal. We wanted to see whether they were actually going to walk the walk and not just talk the talk," Herman Wang, OPEC specialist at S&P Global Platts, told CNBC.
"The 10 members that were required to cut production under this deal have achieved 91 percent, 1.14 million bpd, of cutting from October levels, which was where this deal was benchmarked from."